Vacuum advance mechanism for ignition distributors of internal combustion engines

ABSTRACT

A VACUUM ADVANCE MECHANISM FOR THE BREAKER PLATE IN THE IGNITION DISTRIBUTOR OF AN INTERNAL COMBUSTION ENGINE COMPRISES A HOUSING DEFINING TWO SUCTION CHAMBERS EACH FLANKED BY A SEPARATE DIAPHRAGM. ONE OF THE CHAMBERS IS CONNECTED WITH A FIRST REGION OF THE INTAKE MANIFOLD WHERE THE SUCTION INCREASES WHEN THE ENGINE OPERATES AT PARTIAL LOAD, I.E., WHEN THE SPARK SHOULD BE ADVANCED. THE OTHER CHAMBER COMMUNICATES WITH A SECOND REGION OF THE INTAKE MANIFOLD WHERE THE SUCTION INCREASES DURING IDLING OR COASTING OF THE ENGINE. THE DIAPHRAGMS WHICH RESPECTIVELY FLANK THE ONE AND THE OTHER CHAMBER MOVE OR EFFECT MOVEMENT OF THE BREAKER PLATE IN THE IGNITION DISTRIBUTOR IN OPPOSITE DIRECTIONS WHEN THE SUCTION IN THE RESPECTIVE CHAMBERS INCREASES.

March 23, 1971 H. KALIPPKE E L VACUUM ADVANCE MECHANISM FOR IGNITION DISTRIBUTORS OF INTERNAL COMBUSTION ENGINES 2 Sheets -Sheet 1 Filed Dec. 26, 1968 Nara/d KAI IPPKE Ww/gang Kk/u.

Lea STEIN/(E M/fr/ao JUL/CHER By "7 7 4'/ UI 1/ /Km fire/r ATTORNE Y March lQ7l KALIPPKE ET AL 3,5

VACUUM ADVANCE MECHANISM FOR IGNITION DISTRIBUTORS OF INTERNAL COMBUSTION ENGINES Flled Dec. 26, 1968 ZSheets-Sheet 2 I l 96 2 5U 9m HI /N VE N T095 1 Hora/o KAL/PPKE Eduard L OCHBRUNNEP Wo/fqan K R/Ll Lea S T INKE Wf/frfed JUL/CHER By/f l/fl/r the/ r ATTORNEV United States Patent Patented Mar. 23, 1971 many Filed Dec. 26, 1968, Ser. No. 787,021 Claims priority, application Germany, Jan. 5, 1968, P 16 01 425.8 Int. Cl. F02p 5/10 US. Cl. 123-117 16 Claims ABSTRACT OF THE DISCLOSURE A vacuum advance mechanism for the breaker plate in the ignition distributor of an internal combustion engine comprises a housing defining two suction chambers each flanked by a separate diaphragm. One of the chambers is connected with a first region of the intake manifold where the suction increases when the engine operates at partial load, i.e., when the spark should be advanced. The other chamber communicates with a second region of the intake manifold where the suction increases during idling or coasting of the engine. The diaphragms which respectively flank the one and the other chamber move or effect movement of the breaker plate in the ignition distributor in opposite directions when the suction in the respective chambers increases.

BACKGROUND OF THE INVENTION The present invention relates to improvements in vacuum advance mechanisms for ignition distributors of internal combustion engines.

German utility model No. 1,965,999 discloses a vacuum advance mechanism with two suction chambers which are separated from each other by a flexible diaphragm. The latter is linked to the breaker plate of the ignition distributor and can either delay or advance the spark. The vacuum advance mechanism further comprises a switchover device which connects one of the chambers with the intake manifold when the engine operates at partial load whereby the diaphragm advances the spark and insures complete combustion of fuel. The switchover device connects the intake manifold with the other chamber when the engine is idling or coasting whereby the spark is delayed to insure that the combustion products contain a smaller percentage of toxic ingredients. The position of the diaphragm and of the breaker plate is a function of the pressure differential between the two suction chambers. This creates several problems, particularly as regards proper dimensioning of the diaphragm housing and accurate adjustment of the linkage between the diaphragm and the breaker plate in dependency on the type of the internal combustion engine. A different diaphragm housing must be employed for each type of internal combustion engine. Additional problems arise due to the fact that the diaphragm separates the two suction chambers; therefore, the linkage between the breaker plate and the diaphragm must pass through one of the suction chambers so that the housing must be provided with complicated sealing means to prevent penetration of atmospheric air into that chamber through which the linkage extends. Friction between the sealing means and the linkage can affect the accuracy of the vacuum advance mechanism.

SUMMARY OF THE INVENTION It is an object of our invention to provide a vacuum advance mechanism which can be utilized in combination with or independently of a centrifugal advance mechanism and which is constructed and assembled in such a way that it can be used to advance or to delay the spark in ignition distributors of many types of internal combustion engines.

Another object of the invention is to provide a vacuum advance mechanism wherein the displacing means which transmits motion to the breaker plate of the ignition distributor need not pass through a suction chamber with attendant elimination of problems as regards proper sealing of suction chambers.

A further object of the invention is to provide a vacuum advance mechanism wherein the displacing means which adjusts the breaker plate can be moved without any frictional engagement with other parts of the mechanism.

An additional object of the invention is to provide a vacuum advance mechanism which can adjust the breaker plate within a desired range, either to advance or to delay the spark.

The invention is embodied in a vacuum advance mechanism which comprises a housing defining two suction chambers each communicating with a different portion of the intake manifold in an internal combustion engine, a pair of diaphragms installed in the housing and each flanking a portion of one of the suction chambers to undergo deformation in response to pressure changes in the respective chamber, and displacing means movable in a first direction to thereby displace the breaker plate of the ignition distributor in one direction (to advance the spark) in response to deformation of one of the diaphragms as a result of a drop in pressure in the chamber flanked by the one diaphragm (such drop in pressure takes place when the engine is operated at partial load). The displacing means is further movable in a second direction to thereby displace the breaker plate in another direction in response to deformation of the other diaphragm as a result of a drop in pressure in the chamber which is flanked by the other diaphragm (such drop in pressure takes place during idling or coasting of the engine).

The arrangement is preferably such that the displacing means (e.g., a link or a rod) is connected with the one diaphragm and that the one diaphragm is acted upon by a spring or analogous biasing means which deforms the one diaphragm to move the displacing means in the second direction in response to increasing pressure in the chamber flanked by the one diaphragm simultaneously with decreasing pressure in the other chamber. The mechanism further comprises abutment means provided on or connected with the other diaphragm and arranged to hold the one diaphragm against deformation under the action of the spring when the suction in the chamber flanked by the other diaphragm is low (i.e., when the engine is not idling or coasting). The chamber which is flanked by the other diaphragm is preferably of annular shape and surrounds with clearance the displacing means so that the latter can extend from the housing without any frictional engagement with the parts of such housing.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved vacuum advance mechanism itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawmg.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial sectional view of a vacuum advance mechanism which embodied one form of the invention;

3 FIG. 2 is an axial sectional view of a second vacuum advance mechanism; and

FIG. 3 is a smaller-scale side elevational view of the second vacuum advance mechanism, further showing in axial section the intake manifold and in partial section the ignition distributor of the internal combustion engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a vacuum advance mechanism which comprises a diaphragm assembly 10, a support 11 for the assembly and a casing 12 which accommodates a conventional ignition distributor. The housing of the as sembly 10 is welded to the support 11; this housing comprises two cupped portions including a base portion or bottom 13 and a top portion or cover 14. The bottom 13 accommodates a corrugated ring-shaped carrier 15 of sheet metal which supports an annular diaphragm 16, and a rigid distancing ring 17. A second annular diaphragm 18 is installed between the distancing ring 17 and the cover 14. The marginal portion of the bottom 13 is formed with a shoulder 19 which constitutes an abutment for the annular marginal portion of the carrier 15 and with an inwardly extending annular collar 20 which overlies the marginal portion of the cover 14. The latter defines with the diaphragm 18 a suction chamber 21. The annular central portion of the diaphragm 18 is flanked by two stiffening rings 22, 23 and is coupled to one end of a motion transmitting or displacing link 24 which can adjust the breaker plate in the casing 12. The link 24 extends with substantial clearance through a central aperture 25 in the bottom 13 and with minimal clearance through a slot 26 of the support 11. The central portion of the cover 14 is provided with a s cket 27 for one end of a slightly stressed helical spring 28 which bears against the stiffening ring 22 and reacts against the cover 14 to urge the annular central portion of the diaphragm 18 toward the distancing ring 17. A nipple 29 of synthetic thermoplastic material is sealingly received in an opening of the cover 14 and connects the suction chamber 21 with a suction pipe or hose which is connected to the intake manifold of the internal combustion engine.

The diaphragm 16 defines with the carrier 15 of the housing an annular suction chamber 30 which is sealed from the suction chamber 21. The displacing link 24 extends centrally and with clearance through the space surrounded by the suction chamber 30. A nipple 31 is soldered to the carrier 15 and connects the suction chamber 30 with the intake manifold by Way of a suction conduit or pipe, not shown. The nipple 31 extends through an opening 32 in the bottom 13. The point where the nipple 31 communicates with the intake manifold is located upon the arm of the throttle. The annular inner edge portion 33 of the carrier 15 is bent over the adjoining central portion of the diaphragm 16 and maintains the latter in sealing engagement with a gasket 34.

The diaphragm 16 is connected with an abutment 35 for the diaphragm 18. The abutment 35 is shifted axially against the opposition of a spring 36 in response to increasing vacuum in the suction chamber 30. The central portion of the abutment 35 constitutes a cup provided with a bottom wall 38 which abuts against the stiffening ring 23 at the right-hand side of the diaphragm 18 to maintain the latter against movement beyond the illustrated position. The bottom wall 38 has a central opening 37 for the link 24. The peripheral portion of the abutment 35 is coupled to the diaphragm 16 by several rivets 40 each of which passes through a sealing ring 39. The spring 36 extends centrally through the space which is surrounded by the suction chamber 30 and bears against the bottom wall 38. This spring reacts against the bottom 13 and the latter is provided with an annular head 41 which centers the rightmost convolution of the spring 36. The head 41 surrounds the aforementioned aperture 25 in the bottom 13-. The aperture 25 connects the compartment 9 in the assembly 10- With the atmosphere. This compartment is located between the suction chambers 21 and 30; therefore, each of the diaphragms 16, 18 can operate independently of the other diaphragm. The extent to which the diaphragms 16, 18 are flexed in response to changes in pressure in the chambers 21, 30 can be determined in advance by appropriate stressing of the springs 28 and 36 so as to insure that the vacuum advance mechanism will operate properly at all stages of operation of the internal combustion engine.

The nipple 29 connects the suction chamber 21 with a point immediately upstream of the throttle in the intake manifold. The diaphragm 18 serves as a means for advancing the spark, for example, beyond the advance produced by a conventional centrifugal mechanism of the ignition distributor. As long as the suction in chamber 21 suflices to overcome the bias of the spring 28, the diaphragm 18 is flexed in a direction to the left, as in-. dicated by the arrow, and the link 24 adjusts the breaker plate of the ignition distributor in a sense to advance the spark. The diaphragm 16 serves to delay the spark and is effective when the suction in chamber 21 decreases so that the diaphragm 18 cannot compress the spring 28, i.e., when the spring 28 can urge the stiffening ring 23 against the bottom wall 38 and when the suction in chamber 30 suflices to elfect movement of the abutment 35 in a direction away from the cover 14. The spring 28 then flexes the central portion of diaphragm 18 in a direction to the right to the extent determined by suction in the chamber 30. Such situation arises when the engine is idling or when the engine is coasting because the throttle is then closed and the suction n chamber 30 increases. At the same time, suction in the chamber 21 decreases, i.e., the pressure in the passage of the nipple 29 may rise to atmospheric pressure.

The range of adjustments is limited by the length of two lateral cutouts 42 in the link 24. These cutouts flank a neck portion of the link which is reciprocable'in the aforementioned slot 26 of the support 11. Thus, the maximum spark advance or the maximum delay of spark is determined by the length of cutouts 42, namely, by shoulders 43 which flank the longitudinal ends of the cutouts 42. It is clear that the link 24 can be provided with a single cutout 42 or that the vacuum advance mechanism can be provided with different means for limiting the extent of movement of the link 24 in response to suction in the chamber 21 or 30.

FIG. 2 illustrates a second vacuum advance mechanism which includes a diaphragm assembly comprising a housing composed of a bottom 51 and a cover 54. The bottom 51 has a central opening 52 for a motion transmitting or displacing link 53. The cover 54 has an opening for a plastic nipple 55 which connects a suction chamber 61 with the intake manifold in the same way as described in connection with the chamber 21 and nipple 29. The bottom 51 has a shoulder 59 and an inwardly extending collar 60. The space between the parts 59, 60 accommodates the marginal portion of a .first annular diaphragm 56 and the marginal portion of a rigid distancing ring 57. The suction chamber 61 extends between the cover 54 and diaphragm 56. A slightly stressed helical spring 62 reacts against the cover 54 and bears against a stiffening ring 63 at the left-hand side of the annular central portion of the diaphragm 56. A second stiffening ring 64 is adjacent to the central portion of the diaphragm 56 opposite the ring 63. The left-hand end portion of the link 53 is rigidly connected with the central portion of the diaphragm 56 by way of the rings 63, 64.

The bottom 51 surrounds a second suction chamber 66 which communicates with the passage of a nipple 65. The latter is soldered to the bottom 51 and corresponds to the nipple 31 of FIG. 1. The left-hand side of the suction chamber 66 is sealed by a second diaphragm 58 whose marginal portion is clamped between the shoulder 59 and ring 57. The annular central portion of the diaphragm 8 is connected with an abutment 67 which is a sleeve and is connected with the diaphragm 58 by way of two stiffening rings 68, 69. The sleeve 67 surrounds the link 53 in the interior of the bottom 51. A radial projection 53a of the link 53 can follow axial movement of the sleeve 67 when the vacuum advance mechanism is to delay the spark. i.e., when the sleeve 67 moves in a direction to the right in response to increasing vacuum in the chamber 66 and when the spring 62 is free to push the link 53 in a direction away from the cover 54. The left-hand end of the sleeve 67 forms a collar 70 which is then engaged by the projection 53a. A third annular diaphragm 71 seals the right-hand side of the suction chamber 66. The annular central portion of the diaphragm 71 is flanked by two stiffening rings 72 which are aflixed to the sleeve 67. The marginal portion of the diaphragm 71 is clamped between a shoulder 75 of the bottom 51 and a clamping ring 73. The ring 73 is biased by a prestressed helical spring 74 which operates between the stiffening ring 68 and ring 73 to urge the latter in a direction to the right, as viewed in FIG. 2.

The assembly 50 is mounted on a support 76 which has two tongues 77 facing each other at the opposite sides of the link 53. The tongues 77 extend into cutouts 78 of the link 53 and perform the same function as that portion of the support 11 which extends into the cutouts 42 of the link 24 shown in FIG. 1. The shoulders 79 which flank the longitudinal ends of the cutouts 78 determine the extent of lengthwise displacement of the link 53 in response to flexing of the diaphragm 56 or 58. The tongues 77 are preferably deformable and thus enable an operator to compensate for eventual tolerances in the machining and assembly of parts shown in FIG. 2. Once the springs 62 and 74 are properly stressed, for example, by deforming the housing of the assembly 50, the tongues 77 are moved into registry with reference marks 80 on the link 53. This is the zero setting of the vacuum advance mechanism. This mechanism is used to control an ignition distributor which is further controlled by a customary centrifugal mechanism. The range of adjustments is 3.5 millimeters for spark advance (corresponding to displacement of the ignition distributor shaft through an angle of about degrees) and 3.15 millimeters for delaying the spark (this corresponds to displacement of the shaft through an angle of about 9 degrees). It is clear, however, that the vacuum advance mechanism of our invention can be employed as the only means for advancing or delaying the spark, i.e., without resorting to a centrifugal advance mechanism. The range of adjustments is then altered accordingly.

The compartment 85 in the assembly 50 communicates with the atmosphere by way of the central opening 52 in the bottom 51. Therefore, the diaphragm 56 can be flexed independently of the diaphragm 58 and vice versa. That portion of the compartment 85 which is immediately adjacent to the right-hand side of the diaphragm 56- communicates with the atmosphere through the interior of the sleeve 67. The diaphragm 56 advances the spark by moving in the link 53 in a direction to the left when the suction in chamber 61 suflices to overcome the bias of the spring 62. The diaphragm 58 is effective when the engine is idling or coasting; it causes the sleeve 67 to move to the right whereby the spring 62 pushes the link 53 in the same direction to delay the spark.

When the engine is idling or coasting, the spring 62 moves the diaphragm 56 to neutral or zero position and, as the suction in the chamber 66 increases, the diaphragm 58 overcomes the bias of the spring 74 and enables the sleeve 67 to move in a direction to the right whereby the spring 62 expands and pushes the central portion of the diaphragm 56 (and hence the displacing link '53) in a direction to the right whereby the link delays the spark by effecting appropriate adjustment of the breaker plate in the ignition distributor. Since the two diaphragms operate independently of each other when the suction in the corresponding chambers increases, the vacuum advance mechanism of FIG. 1 or 2 can be used in many types of internal combustion engines because the extent of movement of the displacing link 24 or 53 can be regulated by appropriate stressing of springs which bias the diaphragms 16, 18 or 56, 58.

FIG. 3 illustrates an ignition distributor which is operatively connected with the diaphragm assembly 50 of FIG. 2 by means of the link 53. The nipples 55 and 65 of the assembly 50 are connected with suction conduits 91, 92. The intake manifold 93 of the internal combustion engine contains a throttle 94 whose shaft is shown at 94a. The throttle 94 is illustrated in its closed position; when the throttle opens in response to rotation of the shaft 94a in a counterclockwise direction, as viewed in FIG. 3, the mixture of fuel and air flows in the direction indicated by the arrow. The conduit 91 is connected to an opening 95 of the intake manifold 93 which is located immediately upstream of the throttle 94. When the throttle 94 is held in a partly open position (i.e., when the engine is operated at partial load), the suction chamber 61 in the diaphragm assembly 50 of FIGS. 2 and 3 is maintained under vacuum so that the link 53 adjusts the interrupter device 97 in the housing 90a of the ignition distributor 90 in a direction to advance the spark. The conduit 92 is connected with an opening 96 of the intake manifold; this opening 96 is located downstream of the throttle 94. When the engine is idling or coasting, the throttle 94 is held in closed position and the interior of the manifold 93 downstream of the throttle is maintained at below atmospheric pressure. The suction is communicated to the chamber 66 by way of the conduit 92 whereby the abutment 67 moves in a direction to delay the spark by way of the link 53.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A vacuum advance mechanism for the breaker plate in the ignition distributor of an internal combustion engine having an intake manifold, comprising a housing defining two suction chambers each communicating with a different portion of the manifold; a pair of diaphragms installed in said housing and each flanking a portion of one of said chambers to undergo deformation in response to a pressure change in the respective chamber; displacing means movable in a first direction to thereby displace the breaker plate in one direction in response to deformation of one of said diaphragms as a resultof a drop in pressure in the respective chamber, said displacing means being connected with said one diaphragm and being movable in a second direction to thereby displace the breaker plate in another direction in response to deformation of the other diaphragm as a result of a pressure drop in the respective chamber; biasing means for deforming said one diaphragm and for thereby moving said displacing means in the second direction in response to increasing pressure in that chamber which is flanked by said one diaphragm simultaneously with decreasing pressure in the other chamber; and abutment means provided on said other diaphragm and arranged to hold said one diaphragm against deformation under the action of said biasing means when the suction in the chamber flanked by said other diaphragm is low.

2. A mechanism as defined in claim 1, wherein the chamber flanked by said other diaphragm is of annular shape and surrounds a portion of said displacing means. 3. A mechanism as defined in claim 2, wherein said other diaphragm is of annular shape.

4. A mechanism as defined in claim 1, wherein said abutment means comprises a cupped portion which includes a bottom wall abutting against said one diaphragm when the latter undergoes deformation under the action of said biasing means, said displacing means being arranged to advance the spark on movement in said first direction and to delay the spark on movement in said second direction.

5. A mechanism as defined in claim 4, wherein said abutment means comprises an annular marginal portion affixed to said other diaphragm.

6. A mechanism as defined in claim 5, wherein said other diaphragm is of annular shape and includes annular central and marginal portions affixed to said housing and a median portion afiixed to the marginal portion of said abutment means.

7. A mechanism as defined in claim 1, further comprising second biasing means operating between said housing and said abutment means and arranged to deform said other diaphragm in response to a drop in suction in that chamber which is flanked by said other diaphragm.

8. A mechanism as defined in claim 7, wherein said housing comprises retainer means for said second biasing means and wherein said second biasing means surrounds said displacing means and is surrounded by the chamber flanked by said other diaphragm.

9. A mechanism as defined in claim 1, wherein said abutment means comprises a sleeve and said other diaphragm is of annular shape and comprises an annular central portion affixed to said sleeve, said sleeve surrounding a portion of said displacing means.

10. A mechanism as defined in claim 9, wherein said sleeve and said displacing means comprise cooperating portions which permit movement of said displacing means in said second direction to the extent determined by deformation of said other diaphragm in response to decreasing pressure in the respective chamber, said displacing means being arranged to delay the spark in response to movement in said second direction.

11. A mechanism as defined in claim 10, further comprising a third diaphragm flanking a second portion of the chamber flanked by said other diaphragm, said third diaphragm being of annular shape and having a marginal portion affixed to said housing and a central portion affixed to said abutment means.

12. A mechanism as defined in claim 11, further comprising second biasing means operating between said housing and said abutment means and arranged to deform said other diaphragm in response to decreasing suction in the chamber flanked by said other diaphragm.

13. A mechanism as defined in claim 12, further comprising clamping means securing the marginal portion of said third diaphragm to said housing, said second biasing means comprising a spring reacting against said clamping means and biasing said other diaphragm by way of said abutment means.

14. A vacuum advance mechanism for the breaker plate in the ignition distributor of an internal combustion engine having an intake manifold, comprising a housing definng two suction chambers each communicating with a different portion of the manifold; a pair of diaphragms installed in said housing and each flanking a portion of one of said chambers to undergo deformation in response to a pressure change in the respective chamber; displacing means movable in a first direction to thereby displace the breaker plate in one direction in response to deformation of one of said diaphragms as a result of a drop in pressure in the respective chamber, said displacing means being movable in a second direction to thereby displace the breaker plate in another direction in response to deformation of the other diaphragm as a result of a pressure drop in the respective chamber; and support means for said housing, said support means comprising means for limiting the extent of movement of said displacing means in said first and second directions.

15. A mechanism as defined in claim 14, wherein said limiting means is adjustable.

16. A mechanism as defined in claim 1, wherein said limiting means comprises at least one projection located between two longitudinally spaced shoulders provided on said displacing means.

References Cited UNITED STATES PATENTS 1,845,818 2/1932 Spiller 123117.1 2,268,490 12/1941 Mallory 123117.1 2,557,527 6/1951 Colvin l23117.l

, 2,827,889 3/1958 Smitley 123-1l7.1 3,043,285 7/1962 Bettoni 123l17.l

DOUGLAS HART, Primary Examiner U.S. Cl. X.R. 

